Nicolai Dalchimski, a mad KGB agent steals a notebook full of names of "sleeping" undercover KGB agents sent to the U.S. in the 1950's. These agents got their assignments under hypnosis, so they can't remember their missions until they're told a line of a Robert Frost poem. Dalchimski flees to the U.S. and starts phoning these agents who perform sabotage acts against military targets.

Hoping to bring his family closer together and to recreate his childhood vacation for his own kids, a grown up Rusty Griswold takes his wife and their two sons on a cross-country road trip to the coolest theme park in America, Walley World. Needless to say, things don't go quite as planned.